1. Field of the Invention
The present invention relates to a controller for a transmission having a synchronization mechanism for the number of revolutions, and more particularly to a controller for a transmission having a function of detecting a malfunction in a synchronization mechanism.
2. Related Background Art
There is an already known vehicle-mounted transmission such as an automatic/manual transmission (AMT), in which a motor or some other actuator is used to perform a select operation and a shift operation of a manual transmission (MT) for transmitting power between an input shaft and an output shaft by means of a select operation and a shift operation with a driver's manual operation.
In this type of controller for an automatic manual transmission, the shift operation is performed after synchronizing the number of revolutions of a coupling sleeve with that of an idle gear with the coupling sleeve put in contact with the idle gear arranged relatively rotatable on an input shaft via a synchronizer ring by moving the coupling sleeve rotating integrally with the input shaft. Moreover, it is possible to reduce a shift shock to a driver and to protect the synchronization mechanism for the number of revolutions for long life by absorbing a shock at the synchronization of the number of revolutions.
Therefore, there has been suggested a controller that detects a position (a balk point) where a synchronous friction begins to occur between a synchronizer ring and an idle gear by a rate of change in the number of revolutions of an input shaft, moves a coupling sleeve smoothly with a higher setting of a pressure applied to the coupling sleeve from the start of a shift operation to the balk point, and absorbs a shift shock with a lower setting of the pressure from the balk point (for example, refer to Japanese Laid-Open Patent Publication (Kokai) No. H11-22816 (1999-22816)).
In addition, there has been suggested a controller that determines a balk point by a rate of change in the number of revolutions of an input shaft after starting a shift operation and sets driving current of a shift actuator from the balk point and after to an initial synchronizing current value proportional to a shift load (for example, refer to Japanese Laid-Open Patent Publication (Kokai) No. 2000-46176).
Furthermore, there has been suggested a controller that calculates a progress of a coupling sleeve in a shift operation on the basis of a position, displacement, speed, or the like of the coupling sleeve and determines an occurrence of a gear squeak by the progress (for example, refer to Japanese Laid-Open Patent Publication (Kokai) No. 2002-71005).
In this regard, if the synchronizer ring does not apply the synchronous action in the number of revolutions any more due to an occurrence of a malfunction in the synchronization mechanism when an output of an actuator from the balk point and after is controlled on the basis of the pressure or the shift load in the shift operation of the transmission, the coupling sleeve abuts an idle gear with the number of revolutions being asynchronous, thereby causing a so-called gear squeak.
Furthermore, the above detection of the occurrence of the gear squeak based on the progress of the coupling sleeve is conducted to determine whether the gear squeak has actually occurred. Therefore, it is not available for preventing a damage of the synchronization mechanism associated with the gear squeak.